Researchers combine advanced spectroscopy techniques with medical imaging

Researchers combine advanced spectroscopy techniques with medical imaging

For the first time, the researchers used an advanced analysis technique called dual-comb spectroscopy to rapidly acquire extremely detailed hyperspectral images. By acquiring the full-range information of every pixel in a scene with high sensitivity and high speed, this new method could greatly advance a wide range of scientific and industrial applications, such as chemical analysis and biomedical sensing.

Team leader Pedro Martin Mateos, from the University of Carlos III in Madrid, Spain, said: “Dual-comb spectroscopy provides unparalleled spectral resolution and accuracy and short acquisition times without the need for moving parts. changed spectroscopy.” “Our new direct hyperspectral dual-comb imaging method will have the potential to extend most of the point detection capabilities of current dual-comb systems to create spectral images of entire scenes.”

Dual-comb spectrometers use two light sources, called optical frequency combs, that emit a spectrum of light (or frequencies) that are completely spaced apart like the teeth on a comb. As reported in Optica, the Optical Society’s high-impact research journal, this is the first time a double-comb spectrum has been directly detected using a camera. “We demonstrated spectral interrogation of two-dimensional objects in just one second, three orders of magnitude faster than previous demonstrations,” said Martin Mateos. “This fast acquisition time enables fast or dynamic Dual-comb hyperspectral imaging of the process, which was not possible before.”

Although the work was performed using near-infrared wavelengths, the researchers say the concept can be easily transferred to various spectral regions, expanding the range of possible applications. In particular, extending the method to the terahertz and millimeter-wave spectral regions will open up many new opportunities for non-destructive testing and product inspection in the food, agriculture and pharmaceutical industries. It can also enhance the performance of chemical imaging, 3-D mapping and surface topography techniques in the mid- and near-infrared regions.

demonstrated the optical setup for its new direct hyperspectral dual-comb imaging method. This method extends the point detection capabilities of current dual-comb systems to create spectral images of the entire scene. Image Courtesy: The Pedro MarTIn-Mateos double-comb spectrometer at the Universidad Carlos III de Madrid works by interfering with light from two closely matched optical frequency combs. This mixing process produces signals called interferograms, often at rates of tens of megahertz (millions of times per second) that even the fastest high-speed cameras cannot capture.

“We extended the interferogram generated by the system to a second, allowing the camera to detect the double-comb interferometric signal,” explained Martín-Mateos. “This allows spectral analysis of the entire scene, not just a single point.” Therefore, the researchers built a system based on a very simple electro-optical dual-comb light source consisting mainly of fiber optic components. The use of two acousto-optic modulators allows them to shift the optical comb to arbitrary low frequencies, resulting in ultra-slow interferograms.

The researchers used the new method to obtain hyperspectral images of ammonia gas escaping from the bottle. They achieved an optical resolution of 1 GHz (0.0033 cm-1) at a video rate of 25 frames per second, with each frame containing 327,680 individual spectral measurements. According to the researchers, the resolution they obtained can easily distinguish different gases and is 100 times better than current commercial equipment.

“For example, this allows us to easily identify and differentiate between different gases. The resolution demonstrated in the first experimental demonstration is two orders of magnitude higher than current commercial devices. Simplicity is the key to the system,” says Martín-Mateos. One of the main advantages. “It works flawlessly and can be implemented in any optical lab. “

This work is part of a larger project funded by the ATTRACT programme (Horizon 2020) to develop a fast hyperspectral imaging system that uses the terahertz region of the electromagnetic spectrum for inspection, quality control, and agricultural and food products Classification. The researchers are now working to develop a terahertz dual-comb light source to demonstrate the method in this spectral region.

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